The debut album by One Direction, the boyband put together on The X Factor, has struck a blow for Britain by entering the the US album chart at No 1 – displacing Bruce Springsteen's Wrecking Ball. Up All Night sold 179,000 copies in a week after an intense promotional blitz that had some excitable commentators comparing it to the Beatles' first visit to the States in 1964. Its sales made One Direction the first British pop band to go straight in at No 1 in America with their first LP.

"Whenever we talk to people from the label they don't know what's going on – everyone's just overwhelmed by the reaction," the five-piece band's chief heartthrob, Harry Styles, told the Guardian. "We're just loving it." He described his band's achievement as "incredibly humbling".

His bandmate Zayn Malik played down the Beatles comparisons: "It seems ridiculous for that sort of thing to apply to you – you laugh about it, someone comparing you to such a huge phenomenon."

Though British pop has had a good year internationally thanks mainly to the all-conquering Adele, it is still unusual for a teen pop band from the UK or Ireland to break America – though the Wanted, another British boyband, are also doing well, reaching the top five in America with their song Glad You Came after it was featured on Glee.

In the 90s, the likes of Boyzone and Westlife failed to crack the US market in the face of much slicker homegrown competition from the likes of N Sync and the Backstreet Boys, while Five – also masterminded by Simon Cowell – only managed one top 10 hit in the States, When the Lights Go Out.

Cowell, who signed One Direction to his Syco label after they came third in the 2010 series of The X Factor, said he "couldn't be happier" for the five-piece. "It is an incredible achievement," he added. "They deserve it. They have the best fans in the world."

Last week, Sonny Takhar, the MD of Syco, attributed One Direction's rapid rise in America to their popularity on social media, saying: "Social media has become the new radio, it's never broken an act globally like this before."

"[Social media is] the main thing that we're about," said the band's only Irish member, Niall Horan. "If you ask our fans where they found out about us it's always Twitter, YouTube, Tumblr, Facebook: it's the most powerful thing we have."

Styles said that rather than outsourcing it to a record company employee, the band run their own Twitter feed in order to give fans the personal touch. "It's really important that we connect directly with our fans through the likes of Twitter so they can get to know us. There'd be no point someone in the office doing it because that would defeat the object. We kept in contact with them and gave them something to look forward to. If it wasn't us on the thing, the fans wouldn't know us."

However, music business writer Eamonn Forde was sceptical that social media had played such a significant role in the band's success. He said: "They're signed to Sony, which is the second biggest record company in the world, and they've got the backing of Simon Cowell, the most famous music executive in the world and one of the most famous TV personalities."

He added that the band's six-week US publicity campaign had been organised on time-honoured music industry lines – a gruelling schedule of meet-and-greets in TV and radio stations around the country. The band drew 10,000 fans to their performance on the Today show in New York and have other high-profile TV shows scheduled, including the Nickelodeon Kids' Choice awards and Saturday Night Live.

"They're still primarily promoted by traditional channels," said Forde. "To say they broke on social media would suggest that the machinery behind them was irrelevant and they could have been signed to a tiny indie label or releasing stuff through Bandcamp" - where bands without record company backing can sell music directly to their fans. "In fact, they've got one of the biggest marketing machines in the world behind them."

Nor have One Direction been particularly supported by influential social media figures such as Perez Hilton. Showing that his pop antennae may not be as sharp as he claims, the gossip blogger said of their single What Makes You Beautiful: "Nothing groundbreaking or even particularly interesting here, but harmless and cute. We know they're a boyband but it sounds too young. If they want a huge and long-lasting hit, they need a song with mass appeal."

Forde said One Direction's success is more likely to be because America's biggest teen star, Justin Bieber, who turned 18 this month, is passing his sell-by date, leaving the field clear for other young prentenders. "He's rinsed that career as far as he could. He's done endorsements, he's done a movie – how far can you take this?"

Yet One Direction claim they are unconcerned about the short shelf life of pop bands in America – bandmember Louis Tomlinson said: "We just want to keep working hard and having fun and see what happens. As long as the music's good, people are going to want to go and see us."